This invention relates to a new technique for producing Belgium endive.
The term "endive" is indefinite, for it is loosely applied to two distinct types of chicory plants which are widely used in salads. The exclusive concern of the present invention is with Cichorium intybus or "wild chicory," commercially known as witloof or Belgium endive. This plant has a carrot-like root and deeply lobed and lacinated leaves. The other form of endive, often called escarole, has highly curled leaves.
Since this invention deals only with the first form, we shall hereinafter refer to it as "Belgium endive," particularly since the principal producing area for this plant is Belgium, although substantial amounts are grown in Holland, France and Canada. Currently there is little production of Belgium endive in the United States. One significant aspect of the present invention is that it now makes feasible low-cost production of Belgium endive in the United States and elsewhere, on a year-round basis.
The roots of Belgium endive are sometimes used as a coffee substitute or additive, but the interest of the present invention lies in the young growing shoot that develops in matured roots when subjected to forcing conditions. The culture of Belgium endive is divided into two distinct phases. In the first phase, mature roots are grown in the field using conventional agricultural practices similar to those entailed in carrot or parsnip production. Roots of Belgium endive grown out-of-doors are dug up, after which the tops are removed prior to storage. In some instances, the tops are cut off before the roots are dug up.
The second or forcing phase is started in early fall and is continued throughout the winter and spring months. This phase, as heretofore practiced, cannot be carried out in the summer, for the prevailing temperatures are then too high for forcing Belgium endive. Most forcing takes place in large sheds having a dirt floor, although in mild weather one can effect forcing out-of-doors in soil mounds.
The usual procedure in the forcing phase involves digging a trench across the shed approximately four feet wide and twelve to sixteen inches deep. The roots are then planted one against the other, basal end down, and covered with soil. This process is repeated until the entire floor area of the shed has been planted. In the forcing phase as heretofore practiced, a temperature of about 50.degree. to 60.degree. F is maintained in the shed, and the heads are ready for harvest in about 4 to 5 weeks.
In order to maintain a temperature in the range of about 50.degree. to 60.degree.F in the winter, it is normally necessary to heat the shed. But in the late spring and summer, when the atmospheric temperature rises above this range, production is halted, for it is not commercially feasible to air-condition a shed, particularly since it not only essential to maintain a prescribed temperature level, but it is also important to hold the relative humidity in the range of about 70 to 85 percent.
An excessively high temperature (i.e., above about 60.degree.F) coupled with low humidity in the forcing phase gives rise to soft, open heads of Belgium endive. These are not commercially acceptable. But should the relative humidity fall below 70 per cent, then the shoots become dessicated and brown spots appear which impair the salability of the product. When, on the other hand, a relative humidity in excess of 85 percent prevails, the plant becomes susceptible to disease organisms.
When the growth of Belgium endive is forced in sheds using existing techniques, the following drawbacks are encountered:-